Modal based stability analysis of power systems using energy functions

K. Khorasani, M. A. Pai, P. W. Sauer

Research output: Contribution to journalArticlepeer-review


In this paper a physically based decomposition technique is exploited to perform direct stability analysis of power systems using the energy function method. The slow-coherency analysis decomposes the system into r areas associated with (r- 1) slow modes of the linearized system. The centres of inertia (COIs) of these areas from the slow subsystem and the rest of the fast modes are associated with different areas. The system transient energy function E is decomposed into Eslow associated with the slow variables of the slow subsystem, Efast associated with the fast variables of the r-areas and Efast-slow which is a function of both fast and slow variables. Depending on the fault location and strength of connection between areas, the sum of Eslow, Efast-slow and Efast of the disturbed arease constitutes a good approximation to the system energy function. Using this partial E-function and the potential energy boundary surface (PEBS) method, both Ecr and tcr are computed. Numerical results on a 10-machine 39-bus system are presented in support of the technique.

Original languageEnglish (US)
Pages (from-to)11-16
Number of pages6
JournalInternational Journal of Electrical Power and Energy Systems
Issue number1
StatePublished - Jan 1986
Externally publishedYes


  • network analysis
  • power system element modelling
  • transient stability

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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